The effect of low-temperature annealing on discordance of U–Pb zircon ages

Abstract Discordant U–Pb data of zircon are commonly attributed to Pb loss from domains with variable degree of radiation damage that resulted from α-decay of U and Th, which often complicates the correct age interpretation of the sample. Here we present U–Pb zircon data from 23 samples of ca. 1.7–1...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Maria Herrmann, Ulf Söderlund, Anders Scherstén, Tomas Næraa, Sanna Holm-Alwmark, Carl Alwmark
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/056c31e6c65d48ec82e8488b96584b26
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:056c31e6c65d48ec82e8488b96584b26
record_format	dspace
spelling	oai:doaj.org-article:056c31e6c65d48ec82e8488b96584b262021-12-02T13:26:59ZThe effect of low-temperature annealing on discordance of U–Pb zircon ages10.1038/s41598-021-86449-y2045-2322https://doaj.org/article/056c31e6c65d48ec82e8488b96584b262021-03-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-86449-yhttps://doaj.org/toc/2045-2322Abstract Discordant U–Pb data of zircon are commonly attributed to Pb loss from domains with variable degree of radiation damage that resulted from α-decay of U and Th, which often complicates the correct age interpretation of the sample. Here we present U–Pb zircon data from 23 samples of ca. 1.7–1.9 Ga granitoid rocks in and around the Siljan impact structure in central Sweden. Our results show that zircon from rocks within the structure that form an uplifted central plateau lost significantly less radiogenic Pb compared to zircon grains in rocks outside the plateau. We hypothesize that zircon in rocks within the central plateau remained crystalline through continuous annealing of crystal structure damages induced from decay of U and Th until uplifted to the surface by the impact event ca. 380 Ma ago. In contrast, zircon grains distal to the impact have accumulated radiation damage at shallow and cool conditions since at least 1.26 Ga, making them vulnerable to fluid-induced Pb-loss. Our data are consistent with studies on alpha recoil and fission tracks, showing that annealing in zircon occurs at temperatures as low as 200–250 °C. Zircon grains from these samples are texturally simple, i.e., neither xenocrysts nor metamorphic overgrowths have been observed. Therefore, the lower intercepts obtained from regression of variably discordant zircon data are more likely recording the age of fluid-assisted Pb-loss from radiation-damaged zircon at shallow levels rather than linked to regional magmatic or tectonic events.Maria HerrmannUlf SöderlundAnders SchersténTomas NæraaSanna Holm-AlwmarkCarl AlwmarkNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-11 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Maria Herrmann Ulf Söderlund Anders Scherstén Tomas Næraa Sanna Holm-Alwmark Carl Alwmark The effect of low-temperature annealing on discordance of U–Pb zircon ages
description	Abstract Discordant U–Pb data of zircon are commonly attributed to Pb loss from domains with variable degree of radiation damage that resulted from α-decay of U and Th, which often complicates the correct age interpretation of the sample. Here we present U–Pb zircon data from 23 samples of ca. 1.7–1.9 Ga granitoid rocks in and around the Siljan impact structure in central Sweden. Our results show that zircon from rocks within the structure that form an uplifted central plateau lost significantly less radiogenic Pb compared to zircon grains in rocks outside the plateau. We hypothesize that zircon in rocks within the central plateau remained crystalline through continuous annealing of crystal structure damages induced from decay of U and Th until uplifted to the surface by the impact event ca. 380 Ma ago. In contrast, zircon grains distal to the impact have accumulated radiation damage at shallow and cool conditions since at least 1.26 Ga, making them vulnerable to fluid-induced Pb-loss. Our data are consistent with studies on alpha recoil and fission tracks, showing that annealing in zircon occurs at temperatures as low as 200–250 °C. Zircon grains from these samples are texturally simple, i.e., neither xenocrysts nor metamorphic overgrowths have been observed. Therefore, the lower intercepts obtained from regression of variably discordant zircon data are more likely recording the age of fluid-assisted Pb-loss from radiation-damaged zircon at shallow levels rather than linked to regional magmatic or tectonic events.
format	article
author	Maria Herrmann Ulf Söderlund Anders Scherstén Tomas Næraa Sanna Holm-Alwmark Carl Alwmark
author_facet	Maria Herrmann Ulf Söderlund Anders Scherstén Tomas Næraa Sanna Holm-Alwmark Carl Alwmark
author_sort	Maria Herrmann
title	The effect of low-temperature annealing on discordance of U–Pb zircon ages
title_short	The effect of low-temperature annealing on discordance of U–Pb zircon ages
title_full	The effect of low-temperature annealing on discordance of U–Pb zircon ages
title_fullStr	The effect of low-temperature annealing on discordance of U–Pb zircon ages
title_full_unstemmed	The effect of low-temperature annealing on discordance of U–Pb zircon ages
title_sort	effect of low-temperature annealing on discordance of u–pb zircon ages
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/056c31e6c65d48ec82e8488b96584b26
work_keys_str_mv	AT mariaherrmann theeffectoflowtemperatureannealingondiscordanceofupbzirconages AT ulfsoderlund theeffectoflowtemperatureannealingondiscordanceofupbzirconages AT andersschersten theeffectoflowtemperatureannealingondiscordanceofupbzirconages AT tomasnæraa theeffectoflowtemperatureannealingondiscordanceofupbzirconages AT sannaholmalwmark theeffectoflowtemperatureannealingondiscordanceofupbzirconages AT carlalwmark theeffectoflowtemperatureannealingondiscordanceofupbzirconages AT mariaherrmann effectoflowtemperatureannealingondiscordanceofupbzirconages AT ulfsoderlund effectoflowtemperatureannealingondiscordanceofupbzirconages AT andersschersten effectoflowtemperatureannealingondiscordanceofupbzirconages AT tomasnæraa effectoflowtemperatureannealingondiscordanceofupbzirconages AT sannaholmalwmark effectoflowtemperatureannealingondiscordanceofupbzirconages AT carlalwmark effectoflowtemperatureannealingondiscordanceofupbzirconages
_version_	1718393012228194304

The effect of low-temperature annealing on discordance of U–Pb zircon ages

Ejemplares similares